Motor stator assembly and fabrication method thereof

ABSTRACT

Disclosed is a motor stator assembly comprising: a plurality of yokes manufactured by laminating a plurality of steel sheets having a predetermined length; and a plurality of poles engaged between the yokes and formed by molding magnetic material in a mold, on which coil is wound. In the assembly, material loss can be reduced at the time of blanking operation, and additional protector is not required. According to this, a winding radius of coil is reduced thus to reduce coil amount on the basis of a constant number of times of winding. Also, by using magnetic powder material and silicon steel, productivity is enhanced and motor efficiency is enhanced.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a stator of a motor, and moreparticularly, to a motor stator assembly and a fabrication methodthereof for fabricating a yoke by laminating a plurality of steel sheetsand fabricating a pole by a powder metallurgy method.

[0003] 2. Description of the Related Art

[0004] Generally, most of electric appliances use a motor as a drivingsource. The motor comprises a stator assembly for winding and fixingcoil, and a mover assembly positioned inside or outside of the statorassembly and rotated by induction magnetic field for transmitting adriving force.

[0005]FIG. 1 is a perspective view showing a stator assemblymanufactured by a lamination method in accordance with the conventionalart.

[0006] As shown, the stator assembly comprises: a stator core 1 formedby laminating a plurality of sheets C which are fabricated by blankingsteel with a predetermined shape; an insulator 2 installed in the statorcore 1; and a coil 3 wound outside of the insulator 2 for forminginduction current.

[0007] As shown in FIG. 2, the sheets C constituting the stator core 1includes a yoke 1 a formed as a quadrangle shape for forming a magneticpath; and a pole 1 b formed integrally with the yoke 1 a as a circulararc shape at both sides of an inner circumference surface of the yoke 1a, on which the coil 3 is wound.

[0008] The insulator 2 is attached to a part where the yoke 1 a and thepole 1 b are connected to each other, and is formed with insulatingmaterial such as plastic or rubber for insulating between the coil 3 andthe stator core 1.

[0009] However, in the stator assembly of a lamination method, an amountof scrap loss which is discarded at the time of blanking for fabricatingthe stator core is more than 35%, and accordingly, loss of material isgenerated.

[0010] Also, since a protector manufactured by injection molding, isinserted between the stator core and the coil, a radius of a part wherecoil is wound increases, which result in cost rise, a winding resistanceis increased, and thus a motor efficiency is decreased.

[0011] To solve the above problems, as shown in FIGS. 3 and 4, thestator assembly of powder metallurgy method comprises: a frame 5 formedby inputting magnetic powder material into a mold of a predeterminedshape, applying a predetermined pressure, and heating with apredetermined temperature; and a coil 6 wound on a winding groove 5 c ofthe frame 5 for generating induction magnetism.

[0012] The frame 5 includes a yoke 5 a formed as a closed curve of aquadrangle shape for forming a magnetic path; and a pole 5 b formedintegrally with the yoke 5 a as a circular arc shape at both sides of aninner circumference surface of the yoke 5 a.

[0013] A neck portion of the winding groove 5 c is provided in order toreduce an amount of the coil 6, and an edge of the winding groove 5 c isformed as a curved line in order to prevent coating of the coil 6 fromfalling off when the coil 6 is wound.

[0014] Also, an insulator 7 for insulating the coil 6 from the pole 5 bis attached to an outer side of the pole 5 b and the winding groove 5 cand an inner side of the yoke 5 a which are contacted with the coil 6.However, the powder metallurgy method has a disadvantage that a magneticpermeability of magnetic powder and core loss characteristic are lowerthan silicon steel used in the lamination method and material cost isexpensive.

[0015] Herein, the magnetic permeability is called as magnetic inductivecapacity, which means a ratio between magnetic flux density generated atthe time of magnetization by magnetic field and intensity of themagnetic field in a vacuum state.

[0016] Also, the core loss characteristic means loss generated by steelin a unit volume, and silicon steel has more excellent core losscharacteristic than iron powder. That is, since the silicon steel hasmore excellent magnetic flux density than the iron powder, the motorefficiency is relatively better.

[0017] In the powder metallurgy method, the frame is formed by using themold thus to have an easy fabricating process, the winding groove isformed at the neck portion of the pole thus to reduce consumption amountof the coil, and the curved line is formed at the winding groove thus toprevent the coil from falling off at the time of being wound. However,cost of the magnetic powder is considerably expensive than the siliconsteel.

[0018] Also, since the magnetic powder has low permeability and the coreloss characteristic than the silicon steel, a frame of a larger volumeis required in order to obtain the same effect with a motor using theconventional silicon steel, thereby increasing material cost.

SUMMARY OF THE INVENTION

[0019] Therefore, an object of the present invention is to provide amotor stator assembly and a fabrication method thereof for fabricating ayoke by laminating a plurality of steel sheets and fabricating a pole bya powder metallurgy method, thereby reducing a fabricating cost andenhancing a motor performance.

[0020] To achieve these and other advantages and in accordance with thepurpose of the present invention, as embodied and broadly describedherein, there is provided a motor stator assembly comprising: aplurality of yokes fabricated by laminating a plurality of steel sheetshaving a predetermined length; and a plurality of poles engaged betweenthe yokes and formed by molding magnetic material in a mold, on whichcoil is wound.

[0021] Also, the pole includes: a guide part having a circular arc shapeand for collecting magnetic flux; a winding part connected to a rearsurface of the guide part, on which coil is wound; and a connecting partformed at a rear surface of the winding part and connected to the yoke.

[0022] To achieve these and other advantages and in accordance with thepurpose of the present invention, as embodied and broadly describedherein, there is also provided a manufacturing method of a motor statorassembly comprising the steps of: a first step of forming a plurality ofyoke plates by blanking steel plate of a predetermined shape; a secondstep of forming a yoke by laminating the yoke plates with apredetermined height; a third step of forming a predetermined frame byinstalling the laminated yoke into a mold; a fourth step of fillingmagnetic powder material in an empty space of the mold; a fifth step offorming a pole engaged to the yoke by applying a predetermined pressureand heat to the filled magnetic powder material; and a sixth step ofremoving the mold and then winding coil to the pole.

[0023] In the first step, the yoke plates are formed by blanking thesteel plate having a predetermined length and a width at a time.

[0024] In the fifth step, the pole is formed in accordance with that themagnetic powder material is pressed and then cured with 300˜500° C. thusto be combined one another.

[0025] In the sixth step, when the coil is wound on the pole, aninsulator is attached to a contacted part between the pole and the coil,or insulating material is molded and attached thus to wind the coil.

[0026] The foregoing and other objects, features, aspects and advantagesof the present invention will become more apparent from the followingdetailed description of the present invention when taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this specification, illustrate embodiments of theinvention and together with the description serve to explain theprinciples of the invention.

[0028] In the drawings:

[0029]FIG. 1 is a perspective view showing a motor stator assembly of alamination method in accordance with the conventional art;

[0030]FIG. 2 is a plan view showing the stator assembly of a laminationmethod in accordance with the conventional art;

[0031]FIG. 3 is a perspective view showing a motor stator assembly of apowder metallurgy method in accordance with the conventional art;

[0032]FIG. 4 is a sectional view showing the motor stator assembly of apowder metallurgy method in accordance with the conventional art;

[0033]FIG. 5 is a disassembled perspective view of a motor assemblystator according to the present invention;

[0034]FIG. 6 is a sectional view of the motor assembly stator accordingto the present invention;

[0035] FIGS. 7 to 11 are enlarged views of “A” part of FIG. 6 showing anengagement structure between a connecting part and a yoke of the statorassembly according to the present invention;

[0036]FIG. 12 is a sectional view taken along line I-I of FIG. 6;

[0037]FIG. 13 is an upper surface view of a steel plate showing amanufacturing method of a yoke according to the present invention; and

[0038]FIGS. 14A to 14D are views showing manufacturing processes of themotor stator assembly according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Reference will now be made in detail to the preferred embodimentsof the present invention, examples of which are illustrated in theaccompanying drawings.

[0040] A motor stator assembly and a fabrication method thereofaccording to the present invention will be explained with reference tothe most preferred embodiment.

[0041]FIG. 5 is a disassembled perspective view of a motor assemblystator according to the present invention; FIG. 6 is a sectional view ofthe motor assembly stator according to the present invention; FIGS. 7 to11 are enlarged views of “A” part of FIG. 6 showing an engagementstructure between a connecting part and a yoke of the stator assemblyaccording to the present invention; FIG. 12 is a sectional view takenalong line I-I of FIG. 6; FIG. 13 is an upper surface view of a steelplate showing a fabrication method of a yoke according to the presentinvention; and FIGS. 14A to 14D are views showing fabricating processesof the motor stator assembly according to the present invention.

[0042] As shown in FIG. 5, the motor stator assembly according to thepresent invention comprises: a plurality of yokes 10 manufactured bylaminating a plurality of steel sheets having a predetermined length;and a plurality of poles 20 engaged between the yokes 10 and formed bymolding magnetic material in a mold, on which coil is wound.

[0043] The pole 20 includes a guide part 23 having an inner surface of acircular arc shape and for collecting magnetic flux. The guide part 23is provided to form a magnetic path with a predetermined distance with arotor inserted at an inner side of the stator.

[0044] A winding part 22 is formed at a rear surface of the guide part23 by being integrally connected, and coil is wound on the winding part22.

[0045] A height and a length of the winding part 22 are smaller thanthose of the guide part 23, which prevents the coil 30 from beingprotruded out of the guide part 23 when the coil 30 is wound on thewinding part 22 and so as to wound the coil 30 several times.

[0046] Also, a coil groove 22 a having a thickness t is preferablyformed at an outer circumference surface of the winding part 22 so thatthe coil can be wound thereon. A curved line part 22 b is preferablyformed at an edge of the outer circumference surface of the winding part22 in order to prevent coating of the coil from falling off at the timewhen the coil is wound.

[0047] A connecting part 21 connected to the yoke 10 is integrallyformed at a rear surface of the winding part 22. The connecting part 21has a circular arc shape and the same height with the yoke 10.

[0048] The pole 20 is formed with magnetic powder material for polarity.At this time, a curing process is performed, that is, the powdermaterial is putted into a mold, pressed, and heated with 300-500° C.,thereby being engaged to one another.

[0049] Herein, the number of the poles 20 fabricated by forming themagnetic powder material can be plural, and according to this, thenumber of the yokes 10 can be plural.

[0050] As shown in FIGS. 5 and 6, an insulator 40 for insulating thepole 20 from the coil 30 is attached to at inner sides of the windingpart 22 on which the coil 30 is wound and the pole 20, or nonconductivematerial is molded. And the nonconductive material includes epoxy.

[0051] The plurality of yoke plates 11 having a constant curvatureradius therein are laminated as a height of the connecting part 21, andthe yokes are engaged between two connecting parts 21.

[0052] The yoke plates 11 are formed of silicon steel having excellentpermeability and core loss characteristic.

[0053] Herein, the magnetic permeability is called as magnetic inductivecapacity, which means a ratio between magnetic flux density generated atthe time of magnetization by magnetic field and intensity of themagnetic field in a vacuum state.

[0054] Also, the core loss characteristic means loss generated by steelin a unit volume, and silicon steel has more excellent core losscharacteristic than iron powder. That is, since the silicon steel hasmore excellent magnetic flux density than the iron powder, a motorefficiency is relatively high.

[0055] A connecting projection 11 a and a connecting groove 21 a forengaging the yoke 10 to the connecting part are formed between the yoke10 and the connecting part 21 with the same height as the yoke 10 andthe connecting part 21.

[0056] As shown in FIG. 7, the connecting projection 11 a of the yoke 10is protruded as a rectangular shape, and engaged to the connectinggroove 21 a having a rectangular groove of the connecting part 21 inorder to prevent the yoke 10 from being separated from the connectingpart 21.

[0057] As shown in FIG. 8, the connecting projection 11 a of the yoke 10is protruded as a trapezoid shape, and engaged to the connecting groove21 a having a corresponding trapezoid groove of the connecting part 21.

[0058] As shown in FIG. 9, the connecting projection 11 a of the yoke 10is protruded long with two same stopping jaws 11 a-1 at both sidesthereof, and engaged to the stopping groove 21 a-1 having a groove of acorresponding shape to the connecting part 21 in order to prevent theyoke 10 from being separated from the connecting part 21.

[0059] As shown in FIG. 10, a step projection 11 b of a rectangularshape is formed at both ends of the yoke 10 and engaged to a stepprojection 21 b formed at both ends of the connecting part 21 with acorresponding rectangular shape.

[0060] As shown in FIG. 11, the yoke 10 has a constant inclined surface11 c at both ends thereof and a corresponding inclined surface 21 c isalso formed at both ends of the connecting part 21, so that the yoke 10is engaged to the connecting part 21.

[0061] A fabrication method of the motor stator assembly according tothe present invention will be explained.

[0062] As shown in FIG. 14, thin silicon steel within 1 mm is processedby blanking, thereby forming the plurality of yoke plates 11.

[0063] At this time, as shown in FIG. 13, the yoke plates 11 are formedby processing the silicon steel having a predetermined length and awidth by a punching tool having a plurality of punches at one time.

[0064] According to this, time can be considerably reduced than a casewhen the yoke plates 11 are formed one by one with one punch.

[0065] Then, the yoke plates 11 are laminated with a constant heightthus to form the yoke 10, and the laminated yoke 10 is installed at eachside of the mold thus to form a predetermined frame.

[0066] Herein, if the yoke 10 is filled in the mold, a molding space Cis formed at another part. Magnetic powder material is filled in themolding space C.

[0067] The magnetic powder material is pressed with a predeterminedpressure and heated with a predetermined temperature thus to form thepole 20 engaged to the yoke 10. The pole 20 is integrally engaged to theyoke 10 at the time of molding, instead of engaging the pole 20 and theyoke 10 each other after separately fabricating.

[0068] Also, in order to fabricate the pole 20, the magnetic powdermaterial is pressed and the pressed magnetic powder material is curedwith approximately 300˜500° C. thus to combine the magnetic powdermaterial.

[0069] Herein, the curing is different from sintering slightly. By thesintering, powder material is pressed and heated with temperature closeto a melting point thus to be combined. At this time, since the powdermaterial is combined by heat of high temperature, characteristic of thematerial can be changed.

[0070] On the contrary, by the curing, the powder material is pressedand heated in approximately 300˜500° C. thus to be combined. At thistime, since the powder material is heated by relatively small heat,characteristic of the material is not changed.

[0071] Finally, the mold is removed and then coil 30 is wound on thepole 20 formed of the magnetic powder material.

[0072] When the coil 30 is wound on the pole 20, the insulator 40 can beattached to a part where the pole 20 is contacted with the coil 30, orinsulating material is molded and then the coil is wound.

[0073] The motor stator assembly according to the present invention hasthe following advantages.

[0074] First, whereas the pole is formed of the magnetic powdermaterial, the yoke is formed of the silicon steel which is low and hasmore excellent permeability and the core loss characteristic than themagnetic powder material. Accordingly, a performance deterioration ofthe motor in the same volume can be effectively prevented and thus costincrease by an enlarged motor can be prevented.

[0075] Also, since the yoke plates are processed by blanking with aplurality of punches, time and scrap loss amount are reduced and thusmanufacturing cost is reduced.

[0076] Besides, the groove is formed at the winding part of the pole onwhich the coil is wound and the edge of the groove is formed with acurved line shape. According to this, another coating protecting devicesuch as a protector is not required. Also, winding radius of the coilcan be reduced as a depth of the groove thus to reduce coil amount onthe basis of a constant number of times of winding by approximately 35%.And, by reducing amount of the coil protruded outside the pole and anoverall length of the entire coil, winding resistance is lowered andthus the motor efficiency is enhanced.

[0077] As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalence of such metes and bounds are therefore intendedto be embraced by the appended claims.

What is claimed is:
 1. A motor stator assembly comprising: a pluralityof yokes fabricated by laminating a plurality of steel sheets having apredetermined length; and a plurality of poles engaged between the yokesand formed by molding magnetic material in a mold, on which coil iswound.
 2. The assembly of claim 1, wherein the pole comprises: a guidepart having a circular arc shape, for collecting magnetic flux; awinding part connected to a rear surface of the guide part, on whichcoil is wound; and a connecting part formed at a rear surface of thewinding part and connected to the yoke.
 3. The assembly of claim 1,wherein the pole is formed of iron powder.
 4. The assembly of claim 1,wherein an insulator is attached to inside of the winding part on whichcoil is wound and the pole for insulating the pole from the coil.
 5. Theassembly of claim 1, wherein nonconductive material is molded at aninner side of the winding part on which coil is wound and the pole forinsulating the pole from the coil.
 6. The assembly of claim 5, whereinthe nonconductive material is epoxy.
 7. The assembly of claim 2, whereinthe guide part has an inner surface of a circular arc shape, forcollecting magnetic flux to a rotor by guiding the rotor.
 8. Theassembly of claim 2, wherein a height and a length of the winding partare smaller than those of the guide part in order to prevent the coilfrom being protruded out of the guide part when the coil is wound on thewinding part and in order to wound the coil several times, and an outercircumference surface of the winding part is formed concavely so thatthe coil can be wound thereon.
 9. The assembly of claim 2, wherein anedge formed at an outer circumference surface of the winding part isformed as a curved line in order to prevent coating of the coil fromfalling off when the coil is wound.
 10. The assembly of claim 2, whereinthe connecting part has a circular arc shape and is formed of a platehaving a constant height and a width.
 11. The assembly of claim 10,wherein the yoke is engaged between two different connecting parts andformed in accordance with that a plurality of yoke plates having aconstant curvature radius therein are laminated as a height of theconnecting part.
 12. The assembly of claim 11, wherein a connectingprojection and a connecting groove for engaging the yoke and theconnecting part are formed with the same height as the yoke and theconnecting part.
 13. The assembly of claim 11, wherein the connectingprojection of the yoke is protruded as a rectangular shape and engagedto the connecting groove having a rectangular groove of the connectingpart in order to prevent the yoke from being separated from theconnecting part.
 14. The assembly of claim 11, wherein the connectingprojection of the yoke is protruded as a trapezoid shape and engaged tothe connecting groove having a corresponding trapezoid groove of theconnecting part.
 15. The assembly of claim 11, wherein the connectingprojection of the yoke is protruded long with two same stopping jaws atboth sides thereof, and engaged to a stopping groove having a groove ofa corresponding shape to the connecting part in order to prevent theyoke from being separated from the connecting part.
 16. The assembly ofclaim 1, wherein a step projection of a rectangular shape is formed atboth ends of the yoke and engaged to a step projection formed at bothends of the connecting part with a corresponding rectangular shape. 17.The assembly of claim 1, wherein the yoke has a constant inclinedsurface at both ends thereof and a corresponding inclined surface isalso formed at both ends of the connecting part, so that the yoke isengaged to the connecting part.
 18. A manufacturing method of a motorstator assembly comprising the steps of: a first step of forming aplurality of yoke plates by blanking steel plate of a predeterminedshape; a second step of forming a yoke by laminating the yoke plateswith a predetermined height; a third step of forming a predeterminedframe by installing the laminated yoke into a mold; a fourth step offilling magnetic powder material in an empty space of the mold; a fifthstep of forming a pole engaged to the yoke by applying a predeterminedpressure and heat to the filled magnetic powder material; and a sixthstep of removing the mold and then winding coil to the pole.
 19. Themethod of claim 18, wherein the yoke plates are formed by blanking thesteel plate having a predetermined length and a width at a time in thefirst step.
 20. The method of claim 18, wherein the pole is formed inaccordance with that the magnetic powder material is pressed and thencured with 300˜500° C. thus to be combined one another in the fifthstep.
 21. The method of claim 18, wherein an insulator is attached to acontacted part between the pole and the coil, or insulating material ismolded and attached thereto in order to wind the coil on the pole.